OSX: Keep an explicit reference to our view.

When going fullscreen window, the view gets attached to a new window (of type
NSFullScreenWindow) which causes code that fetches the view from our old window
to fail. This keeps the view reference in our display, which seems to cause
things ot work.

Fixes #1447

Author: SiegeLordEx

src/macosx/osxgl.h

@@ -26,6 +26,7 @@ typedef struct ALLEGRO_DISPLAY_OSX_WIN {
    NSOpenGLContext* ctx;
    NSOpenGLPixelFormatAttribute attributes[AL_OSX_NUM_PFA];
    ALWindow* win;
+   NSView* view;
    NSCursor* cursor;
    CGDirectDisplayID display_id;
    BOOL show_cursor;

src/macosx/osxgl.m

@@ -636,7 +636,7 @@ -(void) enterFullScreenWindowMode
    /* HACK? For some reason, we need to disable the chrome. If we don't, the fullscreen window
       will be created with space left over for it. Are we creating a fullscreen window in the wrong way? */
    [dpy->win setStyleMask: [dpy->win styleMask] & ~NSWindowStyleMaskTitled];
-   [[dpy->win contentView] enterFullScreenMode: [dpy->win screen] withOptions: dict];
+   [dpy->view enterFullScreenMode: [dpy->win screen] withOptions: dict];
    [dict release];
 #endif
 }
@@ -692,7 +692,7 @@ -(void) exitFullScreenWindowMode
     * crash. To avoid it, remove the tracking area and add it back after exiting fullscreen.
     * (my theory)
     */
-   [dpy->win orderOut:[dpy->win contentView]];
+   [dpy->win orderOut: dpy->view];
    [self exitFullScreenModeWithOptions: nil];
    /* Restore the title bar disabled in enterFullScreenWindowMode. */
    if (!(dpy_ptr->flags & ALLEGRO_FRAMELESS)) {
@@ -705,7 +705,7 @@ -(void) finishExitingFullScreenWindowMode
    ALLEGRO_DISPLAY_OSX_WIN *dpy =  (ALLEGRO_DISPLAY_OSX_WIN*) dpy_ptr;
 
    [dpy->win center];
-   [dpy->win makeKeyAndOrderFront:[dpy->win contentView]];
+   [dpy->win makeKeyAndOrderFront: dpy->view];
    [[self window] makeFirstResponder: self];
 }
 
@@ -1583,6 +1583,7 @@ static void init_new_vsync(ALLEGRO_DISPLAY_OSX_WIN *dpy)
 
          return;
       }
+      dpy->view = view;
       /* Hook up the view to its display */
       [view setAllegroDisplay: &dpy->parent];
       [view setOpenGLContext: dpy->ctx];
@@ -1767,7 +1768,7 @@ static void destroy_display(ALLEGRO_DISPLAY* d)
          CGDisplayModeRelease(dpy->original_mode);
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
          if (dpy->win) {
-            [[dpy->win contentView] exitFullScreenModeWithOptions: nil];
+            [dpy->view exitFullScreenModeWithOptions: nil];
          }
 #endif
          CGDisplayRelease(dpy->display_id);
@@ -1776,7 +1777,7 @@ static void destroy_display(ALLEGRO_DISPLAY* d)
       else if (display->flags & ALLEGRO_FULLSCREEN_WINDOW) {
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
          if (dpy->win) {
-            [[dpy->win contentView] exitFullScreenModeWithOptions: nil];
+            [dpy->view exitFullScreenModeWithOptions: nil];
          }
 #endif
       }
@@ -2416,7 +2417,7 @@ static bool set_display_flag(ALLEGRO_DISPLAY *display, int flag, bool onoff)
    bool __block retcode = true;
    dispatch_sync(dispatch_get_main_queue(), ^{
       NSWindowStyleMask mask = [win styleMask];
-      ALOpenGLView *view = (ALOpenGLView *)[win contentView];
+      ALOpenGLView *view = (ALOpenGLView *)dpy->view;
       switch (flag) {
          case ALLEGRO_FRAMELESS:
             if (onoff)
@@ -2457,7 +2458,7 @@ static bool set_display_flag(ALLEGRO_DISPLAY *display, int flag, bool onoff)
                display->flags |= ALLEGRO_MAXIMIZED;
             else
                display->flags &= ~ALLEGRO_MAXIMIZED;
-            [[win contentView] maximize];
+            [dpy->view maximize];
             break;
          case ALLEGRO_FULLSCREEN_WINDOW:
             if (onoff) {